The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

402 / 2024-09-16 12:05:44

Western Pacific deep circulation changes caused by the closure of Indonesian Seaway since the late Miocene

the closure of Indonesian Seaway, Nd isotopic, water mass, Western Pacific deep circulation

The Western Pacific deep circulation is a part of global thermohaline oceanic circulation which distributes fresh water, heat, and geochemical tracers over the globe, thereby profoundly influencing the climate. Despite its critical role in local and global climate, the long-term evolution of the Western Pacific deep circulation remains inadequately understood. Previous literature indicated that, due to closure of Indonesian Seaway, there might be the emergence or intensification of North Pacific Deep Water (NPDW) and reduction in the supply of southern-sourced water to the Pacific deep water, which is mostly based on Nd isotopic records from carbonate and ferromanganese crust. However, these records are proven to be easily influenced by pore water or hydrothermal matter, seeking a reliable proxy linking the closure of Indonesian Seaway and alterations in the Western Pacific deep circulation. Therefore, we offer high-resolution Nd records based on fossil fish teeth, which is not influenced by pore water or hydrothermal matter. Our results from the ODP Site 807, clearly demonstrate progressive variation in water masses associated with the stepwise closure of the Indonesian Seaway, indicating a prominent reorganization of deep water mass since the late Miocene.